# Alpha Centauri (Star)/meta

NOTE CONCERNING STAR POSITIONS:

When comparing real-astronomical star positions to the Traveller Map of Charted Space, it needs to be observed that the axes of the Charted Space Map appear to be tilted almost exactly 45o counter-clockwise from the correct position (i.e. "true" Coreward actually lies parallel to the Lesser Rift). If one makes that adjustment, about 70% of the named stars will fall roughly along their correct bearing. However, there are some exceptions in which the star in question lies in roughly the correct position relative to the Charted Space Map without the need to rotate the coordinate axes.

In general, if one is assigning the position of a Real-Universe star to a Traveller Map hex, it should be acceptable if:

1) The star's longitude angle (θ) is within a 45o bearing-arc between the "true" coordinate axes and the Traveller Charted Space Map coordinate axes, and
2) The star's assigned distance from Terra on the hexmap falls somewhere between its true distance R in parsecs, and its 2D-projection onto the flat map as seen from above, found by Dproj = {R * cos(ɸ)}, where (ɸ) is the latitude angle. If desired, the distance above/below the plane can be determined by Z = {R * sin(ɸ)}.

Note on Alpha Centauri: Alpha Centauri is one of the best illustrations of the axis-problem noted above. Note that Alpha Centauri actually lies at galactic longitude coordinates almost due Coretrailing (315o) from Earth, but is shown as due Trailing (270o) on the Map of Charted Space. This is almost exactly a 45o rotation.

ASTRONOMICAL NOTES: EXOPLANETS:

Alpha Centauri Bc

In March 2015, a transit event of Alpha Centauri B was witnessed possibly corresponding to a planetary body. This planet would most likely orbit Alpha Centauri B with an orbital period of 20.4 days or less and a likely eccentricity of 0.24 or less. If confirmed, this planet would be called Alpha Centauri Bc. It would be far too close to Alpha Centauri B to harbour life.